Abstract: A micro air journal bearing for micro gas turbine engine is designed in this paper. 2D simulation of the aerodynamic micro air bearing is conducted to investigate the effect of the main parameters of the air bearing on the load capacity, including the clearance between the air bearing and shaft, the gear number and height of the air journal bearing, the rotational speed of rotor. The optimum value of the important parameters are explored and presented. The time correlation method is used to solve the RANS (Reynolds Averaged Navier-Stokes) equations. Requirements both from load capacity and motion stability is considered and compromised for a better and stable performance of the air journal bearing. The shaft is stably rotated in a relatively low speed of 1.18×105rpm, which is much lower than other researches and can be achieved easily.

Abstract: Inspired by the squid’s funnel which can bend flexibly, a kind of biomimetic squid funnel actuated by shape memory alloy (SMA) wires was developed for controlling the jet direction in this article. With the application of Pulse Width Modulation (PWM) technique, experimental investigation was conducted. And the results show that, the bending angle of the biomimetic squid funnel can be controlled by changing PWM duty cycle and the final stable resistance of SMA wire decreases while the duty cycle is increased. The relationship between the banding angle of the biomimetic squid funnel and the resistance of SMA wire is approximately inverse linear. The feasibility of jet direction control with the biomimetic squid funnel was verified by a simulated jetting experiment.

Abstract: A new micro EDM method is described. First, the basic principles of micro EDD are
analyzed and realized conditions are predicted. Then with an ordinary EDM shaping machine and
electrode brass, steel and tungsten, a large number of experiments are carried out in air to obtain the
effects of different processing parameters on micro EDD. A micro cylinder with 0.19mm in
diameter and 7.35mm in height is formed on high-speed steel surface. By exchanging the polarities
of electrode and workpiece the deposited material can be removed selectively, thus the reversible
machining is realized. In the end, measurements show that the deposited material is compact and
hardened, whose components depend on the tool electrode material although Zn in brass electrode
is oxidized to ZnO.

Abstract: This paper describes a new surface modification method by Electrical Discharge
Machining (EDM) to create a hard ceramic layer on the workpiece. When a kind of metallic material that makes hard carbide is used as an electrode of EDM, hard ceramic layer can be deposited in a certain condition in the process of EDM. In this paper, characteristics of the layer and the application of this method to cutting tools are discussed. First, the principle of this surface modification method is shown. Secondly, the characteristics of the layer are studied in detail. Through the discuss of wear characteristics of the electrode and formation characteristics of the
layer, it can be found that there are some distinct differences between the traditional EDM technology and this new EDM surface modification method. Thirdly, the micro-hardness test of the layer at the different distance from the base metal is carried out. It shows that there is a hard area also under the surface of base metal. At last, as an application of EDM surface modification method, cutting test of cutting tools is done, and it confirms that the life of the cutting tool by EDM surface modification is much longer than that of without layer.

Abstract: In this paper, an elastic deformation of the axial foil hydrodynamic thrust bearing used in 100KW gas turbine generator is studied. The finite element model of the foil hydrodynamic thrust bearing was established using Solidworks and ANSYS. The foil hydrodynamic thrust bearing which considered foil deformation was analyzed and calculated based on the results of the approximate calculation. The FEA model considered the interaction of plane foil deformation and wave foil. The wave foil was not hypothesized as the linear distributed spring when set up the finite element model. The ANSYS results have demonstrated that the deformation of foil bearing designed based on the result of numerical calculation can meet the requirement of minimal film thickness of bearing lubricant layer.

Abstract: The fabrication of a micro air journal bearing for micro gas turbine engine is investigated based on CAD/CAE and CAM in this paper. Numerical simulation of the aerodynamic micro air bearing is conducted to investigate the bearing load capacity. Then, a removal analysis and contouring strategy of accurate micro-WEDM processing for the air bearing is conducted based on CAM postprocessor. The extended and trimmed tool path is adopted for micro-WEDM. The inner and outer diameter of the bearing is 1.068mm and 1.165mm, respectively. The radius of the bearing corner is 15.9µm, and the height is 53µm.The satisfactory workpiece shape illustrates that the CAD/CAM integrated system is accurate and useful in micro-structures machining.

Abstract: The designing of a micro turbine for micro gas turbine engine is presented in this paper. Micro power system is becoming more and more important for micro- and nano-scale system. The fast development of MEMS (Micro Electromechanical Systems) has strongly enhanced the application of new harder work materials. The fabrication of metallic 3D microstructures has been one of the most attractive topics of micro machining. Currently the basic materials of Micro-turbine Engineering were nonmetal materials such as SiC, most of them are 2D or quasi-3D structures. As a low cost, flexible, good repeatable machining process with negligible process forces, micro-EDM milling is well suited for freeform metallic micro structures. A three-dimensional micro turbine was fabricated by micro-EDM milling. A major problem in micro-EDM milling of complex 3D structure by using micro-electrode is the electrode wear. For reducing the impact of electrode wear, A new CAM system based on the UG software platform is developed in order to get good accuracy 2and higher efficiency. A simple tool path generation by CAD/CAM software and a general electrode wear compensation strategy is presented. The wear compensation can be apart from the design of CAD/CAM systems, so existing common CAD/CAM systems can be used to generate milling tool path with an unequal thickness lamination. And then post process for wear compensation and EDM milling can be done to modify tool path by adding wear compensation. The micro turbine blades of which the material is nickel alloy (GH4169) were successfully fabricated by using this strategy. The diameters of turbine are 2.8mm, and the height of each blade is 0.4mm.

Abstract: This paper discusses a design of a flexible bending biomimetic octopus arm unit. Firstly, bending function of the octopus arm is analyzed. Secondly, the structure of the arm unit driven by shape memory alloy (SMA) is presented which can realize flexible bending. Meanwhile, mechanical model of the arm unit is established to find the proper parameters of the arm unit. Finally, experiments are carried out to demonstrate the feasibility of the structure.